| Objective: To make two kinds of porous titanium specimens with 3D printing technology and analyze its biomechanical properties.In this paper,we discuss the osseointegration of porous titanium implant with the composite coating and 3D printing technology,and provide theoretical support for the clinical experiment of bionic teeth of titanium with composite surface coating and 3D printing technology.Method: 1.To design two kinds of specimen whose aperture size and porosity are different but both of them has the the same size of 5mmx5mmx15 mm through the Geomagic studio2012 and Rhino6.0 modeling software: group A : the inner pore rate of the specimens is 50%,the aperture size is 300 microns,the outer layer porosity is 70%,the aperture size is 500 microns,and thickness ratio is 1:1,whose inside and outside the pass are the square;group B:The overall porosity of the specimens is 50%,and the pore diameter is 300 microns,and the pore type is square.prepare 6 standard specimens for A and B respectively applied 3D printing laser rapid prototyping technology.The yield strength and elastic modulus of the two specimens were compared by using universal testing machine.2.The eight adult male beagles that met the experimental criteria were selected,and were randomly marked as b1-b8.The third and fourth premolars of the right mandible were selected as the target teeth,with 16 teeth(32 root).The original image of the DICOM format of the target tooth was collected by the cone beam CT(CBCT),then imported the image into Mimicis17.0 modeling software and the appropriate threshold was selected and the 3D image of the target tooth was extracted.Used Geomagic studio2012 and Rhino6.0 modeling software design the lower of the implant with gradient of the porous structure(inner layer porosity is 50%,aperture size is 300 microns,the outer layer porosity is 70%,the aperture size is 500 microns,and thickness ratio of is 1:1,both inside and outside are the square)and the smooth circular arc form upper part which is above of the alveolar ridge crestabout 1 mm;the porous titanium bone bionic dental implant were prepared respectively with 3D printing technology,grinding and polishing the upper structure of implant,and then implant for acid corrosion,ultrasonic oscillations,high temperature and high pressure disinfection.Experimental group coated chitosan nanoparticles,no treatment in control group,packaging and set aside.The implant was divided into groups: the control group was the uncoated group,the total number is 16,and the experimental group was the coated chitosan nanoparticle(CSn)group,with 16.The experimental group was coated with CSn and the control group was not treated.Immediately extract the aim tooth of the beagle under general anesthesia,with a flap surgery,cleaning the tooth fossa,implanted into 3D printing titanium bone biomimetic dental implants with 3D printing technology respectively and sutured the wounds without tension,then to observe postoperative of animal life signs and implants saved the situation;Imaging observation and histological observation were performed at 1 month and 3 months after surgery.Results: 1.The average yield strength of the specimens in group A was 184.8±3.9MPa,and the average elastic modulus was 11.9±0.4GPa.The average yield strength of the specimens in group B was 425.4 ± 1.2MPa,and the elastic modulus was 30.3 ± 0.8GPa,and the difference was statistically significant(t=135.7,48.7,p < 0.05).2.Produced 32 porous titanium bone bionic dental implant by the application of 3D printing technology,whose shape is consistent with the basic target of tooth root,the production of high precision,no incomplete,the pore size is consistent,and be connected to each other;After polished,the upper surface of the implant is smooth,without sharp protrusion;The composite coated chitosan nanoparticles were uniform in the experimental group.Extraction the tooth without damaging the alveolar bone wall,no damage to the success of immediate replacement between aim teeth and implant,the right initial stability were perfect,none of the porous structure of implant exposure,32 3D printing porous titanium bone biomimetic tooth implant realized embedded healing;the vital signs of postoperative animals was good,including the four implant from one beagle occurred peri-implantitis due to the cracks of the wound,leading to the failure of the four implants,the remaining 28 implants wound healing were good,peri-implantitis was not occurred,imaging observation shows that the osseointegration between implant and bone tissue were good,no transmission area;Postoperative 1 month histomorphology visible shows that the implant top were covered by attached gingiva both in experimental group and control group,no inflammatory cell infiltration.There were new bone formations on the implant surface,inside and outside pores of the CSn group and the Control group,and no inflammatory cell infiltration was observed.Compared with the Control group,the CSn group was more extensive and tightly bound,and new bones grew in the inner and outer pores.Bone binding is better.The histomorphometric analysis showed that the rate of bone lngrowth rate in Control group and CSn group was 24.6%±2.2% and37.4%±1.8%,respectively(t=7.8,p<0.05).The osseointegration rate in Control group and CSn group was 5.0.% ± 0.4%,24.8% ± 1.5%(t = 21.6%,p <0.05),the difference was statistically significant.Conclusion: 1.The biomechanical properties of group A(the inner pore rate of the specimens is 50%,the aperture size is 300 microns,the outer layer porosity is 70%,the aperture size is 500 microns,and thickness ratio is 1:1,whose inside and outside the pass are the square)is more accord with the design standard of low elastic modulus porous biomimetic tooth,the results of the study can provide experimental basis for the preparation of porous titanium bionic teeth with 3D printing technology.2.The porous titanium bone bionic dental implant system with 3D printing is of high precision,which is basically consistent with the target tooth morphology.3.The 3D printed porous titanium bone bionic dental implant with composite coated chitosan nanoparticles has good bone bonding performance. |
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